Generally, after a vehicle is launched, it is important to identify issues that can affect subsequent launches to mitigate risk of future failure or anomalies. In many cases, assessments are made by comparing flight telemetry data to mission requirements or vehicle family histories. The times of key events are compared to pre-flight predictions. In addition, state vectors at key events are also compared to predictions.
Since event times typically do not agree, comparing other vehicle parameters at various time points becomes difficult or impossible. The lack of a single independent trajectory parameter where comparisons can be made between flight and pre-flight trajectories makes the assessments very challenging for flights having anomalies.
After the assessment, a complete post-flight analysis is conducted for each flight discipline, and a particular activity is focused in areas having anomalous flight data. In some cases, simulation tools can be used to duplicate an anomalous flight event. In other cases, trajectory simulations are used to reconstruct the flight trajectory to show that the flown trajectory was in the family of possible trajectories based on known vehicle or environmental dispersions.
However, this process can be time consuming, expensive, and, in some cases, can lead to ambiguous results. The problem is difficult because flight trajectory time does not match pre-flight predictions due to dispersions and no independent parameter is available to replace time. In addition, the number of parameters to be analyzed is large, and anomalies in one area can affect what happens in another area.
Accordingly, novel diagnostic methods, which may use total orbital angular momentum per unit mass, may be beneficial to compare a pre-flight trajectory with an in-flight trajectory to analyze performance of the vehicle.